Our goal is to develop general analytical methods based on the technique of laser fluorimetry which may be used to detect carcinogens and other biologically active substances in a sensitive and specific manner. Currently, our efforts are directed toward the development of an enzyme-linked laser fluorescence immunoassay of insulin in serum. The method employs antibody bound to Sephadex beads, a beta-galactosidase-insulin conjugate as the labeled antigen, fluorescein-di-beta-D-galactopyranoside as the fluorogenic substrate and a laser fluorimeter-HPLC system to determine enzyme activity by measurement of fluorescence. During the coming year we will continue our work in laser fluorescence immunoassay, with our efforts directed toward more sensitive and simpler methods. One promising direction involves the use of temporal discrimination to reject background fluorescence from interfering components of serum. We will also investigate applications of laser fluorimetry to sandwich immunoassay methods.